The present invention relates to an SPM probe, particularly a self-detecting SPM probe having a piezoresistor.
A scanning probe microscope (SPM) such as an atomic force microscope (AFM) is widely used to observe small region of nanometer order on a sample surface nowadays. The SPM uses an SPM probe which a tip is formed at edge thereof as a scanning probe. In the SPM using the probe, shape of the sample surface is measured by scanning the sample surface with the tip of the SPM probe, and by detecting interaction (attractive force or repulsive force) generating between the sample surface and the tip as bending quantity of the SPM probe.
Bending quantity of the SPM is detected by irradiating laser beam to the SPM probe and by measuring change of the reflected angle. Here, the SPM probe used for this system is called optical lever SPM probe. However, fine adjustment of irradiating angle of the laser beam irradiating to the SPM probe and position of a photodiode detecting the reflected beam from the SPM probe is need at use of the optical lever SPM probe. Particularly, there has been complicated that the fine adjustment should be repeated at exchange of SPM probe carried out frequently.
Then, a self-detecting SPM probe detecting bending quantity of the SPM probe by forming a piezoresistor at the SPM probe and by measuring change of the resistance value is drawing public attention.
Constitution of the conventional self-detecting SPM probe is shown in FIG. 13 and FIG. 14. FIG. 13 is a plane view and FIG. 14 is a sectional view taken along line D-Dxe2x80x2 of FIG. 13. As shown in FIG. 13, a self detecting SPM probe 100 comprises an SPM probe 102 having a tip (not shown) at edge thereof and a reference 104 for measuring reference resistor value. These SPM probe 102 and reference 104 form U-shaped piezoresistors 108 and 110 each on surface thereof. Here, the piezoresistors 108 and 110 are formed on an n-type silicon substrate 106 as injecting selectively p-type impurity ion in U-shape each as p+ piezoresistor.
Moreover, as shown in FIG. 14, silicon oxide film (SiO2) 112 protecting the surface except a metal contacting portion of the SPM probe and a metal contacting portion of the reference 104 is formed. Aluminum electrodes 114, 116, 118, and 120 for contacting are produced at each of metal contacting portions. Although p+ piezoresistors 108 and 110 are formed at surface of n-type silicon substrate 106 by injecting p-type impurity ion, reversely at use of p-type silicon substrate, n+ piezoresistors are formed by injecting n-type impurity ion.
Observation of the sample surface by the above conventional self-detecting SPM probe 100 is carried out by scanning the sample surface with the SPM probe 102 where a tip is formed at edge portion thereof first. Interaction (attractive force or repulsive force) generating between the sample surface and the tip bends the SPM probe 102, and the bending changes resistance value of the piezoresistor 108 formed on the SPM probe 102. The resistance value is detected as bending quantity of the SPM probe 102. Change of resistance value of the piezoresistor 108 is led to a signal processing portion (not shown) through the above-mentioned aluminum electrodes 114 and 116 of the metal contacting portion so as to make image as signal showing the sample surface.
At the same time as the above operation, measurement of resistance value is carried out at the reference 104. This measurement provide reference resistance value for removing unnecessary data of changing from change of resistance value measured at the SPM probe because of changing by condition except bending of temperature and so on. Temperature compensation is realized at detecting using a bridge circuit.
The self-detecting SPM probe using the above piezoresistor is disclosed in Japanese Opened Patent No. 5-116458 and U.S. Pat. No. 5,345,815.
As above-mentioned, as a detector detecting bending quality of the SPM probe, namely the piezoresistor is formed at the probe itself in the case that the self-detecting SPM probe is used for a scanning probe microscope, complicated operation such as position adjustment of the detector like the conventional optical lever are not need at exchange of the SPM probe so as to speedily start observation of the sample.
The conventional optical lever SPM probe has been able to measure change of bending of the SPM probe based on capacitance induced by change of current flowing between a tip and a sample surface or supply of voltage which is supplied between the tip and the sample surface by the tip having conductivity. Particularly, Kelvin probe force microscope (KFM) or scanning Maxwell stress microscope is used as microscope supplying voltage between the tip and the sample surface using the conductive SPM probe and measuring voltage and the like of the sample surface.
However, the conventional optical lever SPM probe enable to measure voltage of the sample surface generally has had conductivity at only the whole SPM probe including a tip or surface thereof. As the self-detecting SPM probe forming a piezoresistor on the SPM probe can not have conductivity at the whole of SPM probe including the tip, the probe has not been used for the above KFM and SMM.
The present invention is provided in view of inconvenience the above prior art. An object of the invention is to provide an SPM probe enabling to detect bending quantity of the SPM probe by a piezoresistor formed at the SPM probe and to measure voltage a sample surface.
To solve the above-mentioned problem and achieve the object, an SPM probe according to the invention of a first aspect is characterized by that conductive film formed on is covered at said tip and near by the tip in the SPM probe comprising a lever portion which a sharpened tip is formed at edge thereof and a supporting portion for supporting the lever portion.
According to the present invention of the first aspect, as the tip has conductivity by covering the conductive film at the tip surface, it is possible that voltage is supplied between the sample being one side of electrode and the tip by taking out wiring from the conductive film for another side of electrode. As the whole of SPM prove does not have conductivity, mixing of noise can be protected.
An SPM probe according to the invention of a second aspect is characterized by that wiring is taken out from vicinity of said tip of said conductive film in the first aspect.
According to the SPM according to the present invention of a second aspect, it is possible to prevent heating of the SPM probe by voltage supply and to supply high voltage being small in loss by taking out wiring from the conductive film covering the tip surface and by selecting material being high in conductivity as wiring.
An SPM probe according to the invention of a third aspect comprises a lever portion forming a sharpened tip at edge thereof, a supporting portion for supporting the lever portion, and a bending portion connecting said lever portion and said supporting portion. The SPM probe is characterized by that conductive film is covered at said tip and vicinity thereof, insulation layer is formed on said piezoresistor and said supporting portion, and conductive layer connecting electrically to said conductive film at vicinity of said tip of said conductive film and connecting to said supporting portion through said bending portion from said lever portion in the U-shaped SPM probe passing said bending portion.
According to the present invention of the third aspect, as the probe has conductivity by covering the conductive film at the tip surface, one side of electrode is formed wiring the conductive layer from the conductive film and it is possible to supply voltage between the sample being another side of electrode and the tip. As whole of the SPM probe does not have conductivity, it is possible to prevent heating of the SPM probe by voltage supply and to supply high voltage being small in loss. It is possible to measure interaction between the sample surface by detecting bending quantity of the SPM probe caused by the piezoresistor and the tip and to measure voltage of the sample surface without using a detector needing complicated adjustment.
An SPM probe according to the invention of a fourth aspect is characterized by that said conductive layer is formed on said conductive film at part connected electrically between said conductive layer and said conductive film in the invention of the third aspect.
According to the invention of the fourth aspect, as the probe has conductivity by covering the conductive film at the tip surface, one side of electrode is formed wiring the conductive layer from the conductive film and it is possible to supply voltage between the sample being another side of electrode and the tip.
An SPM probe according to the invention of a fifth aspect is characterized by that said conductive layer is formed under said conductive film at part connected electrically between said conductive layer and said conductive film in the invention of the third aspect.
According to the invention of the fifth aspect, as the probe has conductivity by covering the conductive film at the tip surface, one side of electrode is formed wiring the conductive layer from the conductive film and it is possible to supply voltage between the sample being the other side of electrode and the tip.
An SPM probe according to the invention of a sixth aspect is characterized by that conductive region is formed injecting ion in said tip in the SPM probe comprising a lever portion forming a sharpened tip at an edge thereof and a supporting portion for supporting the lever.
According to the present invention of the sixth aspect, the tip can have conductivity without losing sharpness by forming the conductive region by ion-injection at part forming the tip. Therefore, it is possible that voltage is supplied between the sample being one side of electrode and the tip by taking out wiring from the conductive film for the other side of electrode. As the whole of SPM prove does not have conductivity, mixing of noise can be protected.
An SPM probe according to the invention of a seventh aspect is characterized by that wiring is taken out from vicinity of said tip of said conductive region in the invention of the sixth aspect.
According to the present invention of a seventh aspect, the electrode wiring can be taken out from conductive region formed at the tip, and it is possible to prevent heating of the SPM probe by voltage supply and supply high voltage being small in loss by selecting high material high in conductivity as the electrode wiring.
An SPM probe according to the invention of a eighth aspect comprises a lever portion forming a sharpened tip at edge thereof, a supporting portion for supporting the lever portion, and a bending portion connecting said lever portion and said supporting portion. The SPM probe is characterized by that conductive region is formed in said tip by ion injection, insulation layer is formed on said piezoresistor and said supporting portion, and conductive layer connecting electrically to said conductive region at vicinity of said tip of said conductive region and connecting to said supporting portion through said bending portion from said lever portion.
According to the present invention of the eighth aspect, as the probe forms tip conductive region by ion-injecting at part forming the tip, the tip can have conductivity without losing sharpness. Therefore it is possible to supply voltage between the sample being one side of electrode and the tip by making another electrode taking out wiring from the tip conductive region. As whole of the SPM probe does not have conductivity, it is possible to prevent mixing noise, to prevent heating of the SPM probe by voltage supply, and to supply high voltage being small in loss.
An SPM probe according to the invention of ninth aspect comprises a lever portion forming a sharpened tip at edge thereof, a supporting portion for supporting the lever portion, and a bending portion connecting said lever portion and said supporting portion. The SPM probe is characterized by that a piezoresistor is formed on the SPM probe, insulation layer is formed on said piezoresistor and said supporting portion, and conductive layer covering said tip and vicinity thereof and connecting to said supporting portion through said bending portion from said lever portion.
According to the invention of ninth aspect, the SPM probe forming the piezoresistor has conductivity at the tip surface and the conductive layer from the tip surface. Therefore, it is possible to measure interaction between the sample surface by detecting bending quantity of the SPM probe caused by the piezoresistor and the tip and to measure voltage of the sample surface without using a detector needing complicated adjustment. By selecting material of the conductive layer led from the tip, an SPM probe having a priority in sharpness of the tip and an SPM probe having a priority in conductivity of wiring led from the tip can be provided. Therefore, users can select a suitable SPM probe for object of use or the observed sample.
An SPM probe according to a tenth aspect is characterized by that an identification mark for identifying a position in a semiconductor wafer is formed at said supporting portion when said SPM probe is formed on the semiconductor wafer and is taken out being separated from said the semiconductor in any of the first to ninth aspects.
According to the invention of the tenth aspect, the identification mark for identifying a position on the semiconductor wafer mark is formed at the SPM probe formed at the semiconductor wafer as the SPM probe. As the position on the semiconductor wafer in which the SPM probe is formed can be identified, positional distribution of rejected SPM probes on the wafer can be obtained for the rejected SPM probes by reading out the identification mark even if the SPM probe is taken from the semiconductor wafer.
The invention of an eleventh aspect is characterized by that a device is the device using any of the SPM probes of the first to tenth aspects. As adjustment of a laser beam is not needed because a self-detecting type cantilever is used in the device as compared with the conventional optical lever type device, and operation of the device is easy. Noise is decreased by forming an exclusive electrode so as to measure more accurately.